Holocene Soil Formation Research Articles

Loess in Pleistocene periglacial slope deposits and Holocene colluvium of European low mountain ranges: Mixing processes and spatial variations

Loess, as an allochthonous material, plays a significant role in the formation of Pleistocene periglacial slope deposits (PPSD), and thus also for Holocene soil formation, in the central European low mountain range. Although the differing loess proportions in different layers of the PPSD have been well recognized, quantitative distribution and mixing processes of loess in PPSD are still not fully understood. Detailed particle-size distribution was applied for quantifying loess proportions in PPSD in a sandstone area in central Germany. The bimodal pattern of the particle-size distribution curves clearly reflected loess and sandstone-weathering material as two components of the loess-affected layers, which allowed for the quantification of these two components by applying a two-endmembers unmixing model. By inspecting variations of particle-size distribution curves both vertically and spatially, we gained insights into the mixing processes of loess in PPSD and Holocene colluvium. Our results suggest that the loess component in upper layers most likely results from the incorporation of preexisting loess. Holocene colluvium and upper layers were thoroughly homogenized by various earth-surface processes. Radiocarbon dating of charcoal indicated strong human impact during historic times. Close correlation between the overall thickness of loess-containing layers and the depth-weighted loess content pointed to the erosional-depositional history at each site. Our research demonstrates the utility of detailed particle-size data for detecting and interpreting geomorphological processes and landscape evolution. It shows that the spatial distribution patterns of loess are subjected not only to topographic factors controlling primary loess deposition, but also to erosional-depositional histories and anthropogenic impact.

Trend of increasing Holocene summer precipitation in arid central Asia: Evidence from an organic carbon isotopic record from the LJW10 loess section in Xinjiang, NW China

Due to the lack of reliable climatic proxies, the variability of precipitation in “Westerlies-dominated” arid central Asia (ACA) during the Holocene is debated. Here, we present a high-resolution (ca. 100 years per sample) organic carbon isotopic composition (δ13Corg) record from bulk samples from the Lujiaowan10 section in the northern piedmont of the Tienshan Mountains, Xinjiang Province, northwestern China. A robust chronology is provided by K-feldspar pIRIR dating. During the early to middle Holocene, from 12 ka to 6 ka (1 ka = 1000 years ago), the δ13Corg values are relatively invariant with an average of around −22.5‰. After about 6 ka, the δ13Corg values exhibit an overall negative trend with the most negative value of −25.2‰ occurring in the uppermost part of the section, within the interval of Holocene soil formation. Our investigation of the relationship between modern climatic variables and surface soil δ13Corg values from the region reveals a significant negative correlation between surface soil δ13Corg and summer precipitation amount (June to August). Therefore, we used the calibration model between summer precipitation amount and surface soil δ13Corg to quantitatively reconstruct the Holocene summer precipitation history of the study area. Our results indicate that summer precipitation in the region was the lowest (ca. 85 mm) during the early to middle Holocene (12–6 ka); however, after 6 ka, the precipitation increased continuously to about 137 mm per year at the present. Our reconstruction is generally consistent with climate simulation results and with regional effective moisture records. Thus, we conclude that the highest summer precipitation, and therefore the wettest climate, occurred in the late Holocene. Decreasing Northern Hemisphere summer insolation may have effected a change in the CGT (circumglobal teleconnection) from a positive to negative phase and, together with more negative trends in AO (Arctic Oscillation) or NAO (North Atlantic Oscillation), may have been responsible for the observed pattern of summer precipitation evolution.

Spatial variability of Late Pleistocene–Early Holocene soil formation and its relation to early human paleoecology in Northwest Mexico

In Sonora, northwest Mexico, we have recognized the existence of paleosol units of Late Pleistocene/Early and Middle Holocene age (13,000 to 4,250 Cal years BP) at several archaeological sites with Paleo-indian occupations (e.g. La Playa, Fin del Mundo, El Bajio, El Aigame and El Arenoso). The few paleoenviromental reconstructions from the region indicate that the end of the Pleistocene was dominated by temperate climate that promoted the establishment of the first people in coexistence and interaction with the Pleistocene megafauna. The study of the spatial distribution of various soil units developed during late Pleistocene in the region provides information about local environmental settings of the initial peopling of Sonora. Several pedosedimentary sequences were analyzed in the different parts of Sonora, the age control in which was provided by archaeological and paleontological findings and/or by the radiocarbon dating of carbonates and paleosol humus.Two trends of the Late Pleistocene pedogenesis have been identified. The profiles located in the south, center and north of the state are dominated by red soils (earlier referred as Big Red in the archaeological literature) whose characteristics are represented by the Red San Rafael Paleosol (SRP). The properties of SRP in the lower part of the profile (rubification, clay accumulation, hig magnetic susceptibility, illuvial carbonates, and redoximorphic features) are indicative of a more humid environment. Above them is a late Holocene polycyclic sequence of soils with morphological characteristics displaying a more incipient development.In contrast with the sequence described above, El Arenoso, north of Caborca, show a sequence of gray soils. Two paleosols were formed in alluvial sediments. At the Cantera profile (CTP) and El Arenoso profile (ARP) paleosols are represented by Bgk horizons and evidence of weathering and clay neoformation, redoximorphic processes and illuvial accumulation of carbonates. We explain the differences of north-western profiles by specific geomorphic conditions which imply limited soil drainage and the possibility of over-wetting. These processes indicate alternating a humid environment (weathering, rubification, clay formation and redoximorphic processes); and dry periods (carbonates accumulation). Despite regional differences of the late Pleistocene paleosols, the comparison with the Holocene soils demonstrates clear trends towards desertification in the region. The first people that inhabited Sonora during the late Pleistocene found a more temperate and wetter climate than they encountered further to the north, but subsequent generations witnessed a rapid desiccation of the region with the formation of the Sonoran Desert in the early Holocene.

When Holocene soil formation starts on the loess plateaus of the Vojvodina region in Northern Serbia

In this study we evaluated simplified direct comparisons between Pleistocene regional and local terrestrial environmental archives and global deep sea and ice core records. Our recent results of the luminescence dating applied to the Serbian loess-paleosol sequences lead to an important question about the validity of previously generalized direct stratigraphic correlations, as well as to underline importance of understanding environmental thresholds which controlling discordances between these paleoclimatic records.

Formation and transformation of Pleistocene periglacial slope deposits in the Spessart Mountains (Hesse, Germany)

The bedrock of the Spessart Mountains is covered by Pleistocene periglacial slope deposits (PPS- Ds). These slope deposits are supposed to have formed in a periglacial environment by a variety of processes. For this study soil profiles in the Spessart Mountains were analyzed with respect to features elucidating processes forming and transforming PPSDs. Field and laboratory analyses were complemented by micro- morphological investigations to gain more detailed information. The results verify aeolian sedimentation, solifluction and cryoturbation as most important formation processes. Furthermore, several findings sug- gest the influence of additional genetically active processes. PPSDs provide the parent material for Holocene soil formation. In addition, they experience alteration by bioturbation and anthropogenic influence on relief and soil. Pedogenic transformation is dependent on the PPSDs material composition. Particularly the content of silt-sized allochthonous material controls the efficacy of silicate weathering and depth of soil development. The coincidence of pedogenic boundaries and layers often reported in the literature is partly falsified: Eluviation and illuviation of clay is not separated at the boundary between upper and intermediate layer. PPSDs experience strong alteration by bioturbation: This process may transform characteristics that could point to formation processes. Furthermore, thin sec- tion analyses support the distinction of Holocene colluvium and PPSDs.

Environmental dynamics and luminescence chronology from the Orlovat loess-palaeosol sequence (Vojvodina, northern Serbia)

The Carpathian Basin contains some of the best preserved loess deposits in Europe, including some of the continent's longest and best resolved climate records. Large areas of the basin have been intensively investigated in recent years, although deposits in the east remain largely unstudied, despite considerable regional variation in climate records. Here we discuss the sedimentary record exposed in the Orlovat brickyard using detailed litho- and pedo-stratigraphic, enviromagnetic parameters and luminescence dating. The results show an atypical Late Pleistocene succession for the Carpathian Basin. Notably, the normally widespread pedocomplex V-L1S1 is missing. This contrasts with other parts of the sequence, which appear highly resolved, such as the thicker pedocomplex V-S1 and the detailed transitions between modern pedocomplexes V-S0 and the last glacial loess unit V-L1. The luminescence chronology demonstrates a lack of intensive pedogenesis during the Early Holocene and raises an important general question about the beginning of Holocene soil formation in the region. The later Holocene soil formation adds to a growing body of evidence that suggests more complex terrestrial responses of climate to global climate change. This evidence weakens the validity of previously generalized direct stratigraphic correlations between regional terrestrial environmental archives, and global marine and ice core records. Copyright # 2014 John Wiley & Sons, Ltd.

Characterisation of Andosols from Laacher See tephra by wet-chemical and spectroscopic techniques (FTIR, 27Al-, 29Si-NMR)

At 12,900aBP, the eruption of the Laacher See volcano generated a new parent material for Holocene soil formation in parts of Western Germany. Weathering of these ashes commonly includes the formation of poorly crystalline minerals such as allophane, imogolite and ferrihydrite. Detection of these minerals in soil is difficult, yet an important task, because they may govern soil functions and processes, e.g., stabilisation of organic matter and nutrient availability. Therefore, we characterised three forested Andosols by a combination of wet-chemical and spectroscopic techniques including infrared and (27Al, 29Si) nuclear magnetic resonance (NMR) spectroscopy together with X-ray diffractometry. Deconvoluting the 29Si-NMR spectra revealed that 1.6 to 10.4% of total Si was present as allophanic compounds, which coincided with the amounts of oxalate-extractable Si. Since extraction methods are not completely selective, we observed a slight overestimation of allophanic Si estimated from oxalate extraction. Although the sites under study are located close to each other in similar relief positions and with similar vegetation, the combination of our results revealed varying amounts of loess in the parent materials and varying weathering intensity. High weathering intensities correlate with the amounts of allophane.

Holocene soil formation and soil erosion at a slope beneath the Neolithic earthwork Salzmünde (Saxony-Anhalt, Germany)

Abstract Phases of formation and erosion of Holocene soils were reconstructed based on a sequence of buried soil horizons and colluvial layers at a lower slope section beneath the Neolithic earthwork of Salzmunde, Germany. The chronology is based on eight radiocarbon ages of charcoal, soil organic matter as well as on archaeological age estimations of embedded artefacts. Until ca. 2200 BC, a chernozemic A–C-soil developed in fluvially redeposited loess. The occurrence of charcoal, the darker colour, and a shift of soil matrix radiocarbon age indicate an alteration of the upper part of the humus horizon probably related to anthropogenic activities at ca. 2200 BC. This soil was probably buried rapidly by a colluvial layer (at ca. 2200 BC). Until ca. 900 AD, a phase of less intensive land use with slope stability followed. During this phase a pedogenetic alteration — probably under forest cover in the watershed and the deposition area — of the upper part of the loess, the buried soil, and the prehistoric sediment occurred (formation of chernozem cambisol). The upper part of a dated humic crotowina fill was involved in pedogenesis as well. Soil formation is indicated by changes in soil colour (brown), pedogenic iron, clay content, the mineral assemblage of the clay fraction, and magnetic susceptibility. During medieval times (ca. 900–1500 AD), two colluvial layers with a cumulative thickness of about 1 m buried this soil. The partial destruction of the archaeological remains at the plateau started at this time. During modern times (since 1500 AD), the deposition of two colluvial layers of a cumulative thickness of about 1 m completed the sequence of Holocene slope deposits. The results imply that the chernozem at the site might have been altered by prehistoric land use and altered further into a chernozem cambisol during a phase of slope stability of about 3000 years between the Bronze Age and medieval times. The detected brunification processes took place at unexpected high rates.

The regularities of the late Holocene soil formation in the lower don steppes

The direction and stages of pedogenesis, rate and scales of changeability, and type of evolution of chernozems in the steppes of the Lower Don are ascertained by studying the archaeological monuments of the Bronze Age, Early Iron Age, and Middle Ages. It is shown that the soil formation process was characterized by cyclicity, and evolutional soil transformations took place at the level of subtype. The paper ascertains the polygenetic character of modern chernozems, whose evolution during the second half of the Holocene was predominantly low-contrast, inheriting, and transforming. The processes forming the humus, salt, gypsum, and carbonate profiles, as well as the processes of solonetzization-desolonetzization, were the most dynamic. The fundamental differences in the genesis of different parts of the humus profile are revealed. The role of climatically pulsing solonetzicity in forming the specific Azov chernozems is for the first time ascertained.

Durations of soil formation and soil development indices in a Holocene Mediterranean floodplain

Holocene and late Pleistocene alluvial sequences of the mid-Medjerda floodplain (Northern Tunisia) reveal three types of soils with gradual transitions: Fluvisols (Calcaric), Cambisols (Calcaric) and Calcic Luvisols (Chromic). Stratigraphic cross-correlations, palaeomagnetic secular variation, and 14C and IRSL dating enable detailed information about ages and durations of soil formation in the floodplain. Weakly developed Fluvisols (Calcaric) commonly reveal late Holocene ages with soil formation durations lasting between 100 and 300 years. Hence, Holocene soil formation is detectable in the exposures from durations of around 100 years onwards. Cambisols show predominantly mid-Holocene ages. The durations of soil formation are between 800 and 5000 years. Calcic Luvisols (Chromic) feature late Pleistocene ages, with durations of soil formation between 10,000 and 40,000 years. Profile Development Indices were computed from simple field parameters like soil structure, soil colour, horizon thickness and leaching features. The derived development indices show good correlation ( R 2 = 0.804) with the calculated durations of soil formation. Field parameters are well suited for a quantitative development index of Holocene soil formation, even if very weak developed soils are predominant. The study shows that maturity stages of Holocene alluvial soils in a homogeneous Mediterranean environment are predominantly driven by soil formation duration.

Paleosols in the moraine-mantle loam sequence of northeastern Europe: The memory of pedogenesis rates and evolution of the environment during OIS3

Morpho-analytical features of the paleocatena (a complexly organized heterochronous sequence), which contains 2 pedostratigraphical units: formed on the Holocene mantle loams Umbric Albeluvisol and the underlain Middle Valday (Wűrmian) paleopedocomplex developed on Moscowian (Riss II) moraine deposits, are described. The buried pedocomplex consisted of: 1) the paleohumus and paleogley (2Atgb–2Gtb–3Atgb) and 2) paleohumus (3Atgb–3AtGb) horizons. Thus, these pedostratigraphic units reflect two studies of pedogenesis marked by two paleohumus horizons. The horizons of the paleopedocomplex are separate parts of the profile classified as the Umbric Gley soil formed during OIS3. The 14C age of the three paleosol horizons varied between 24,350–30,900 yr BP. The studied paleopedocomplex is the only one known containing the Middle-Valday paleosol formed on moraine deposits, which is a clear sign of the northernmost occurrence of the Bryansk fossil soil in Europe. A detailed hierarchical morphological study of the paleopedocomplex, including meso- and submicromorphological and magnetic susceptibility analyses, allowed us to identify the Late Quaternary pedogenic processes under severe extra-continental climate, including gleyzation, aggregation, cracking and humus formation. Good preservation of these individual pedogenic processes is shown to be a soil memory under the overlapping press of Holocene pedogenesis. It was shown that the clay coating in the Middle Valday of the pedocomplex is a part of the Holocene soil formation. Based on the palynological data, it is possible to subdivide the development of paleovegetation of the area into four stages during which the paleosol horizons had being formed. At the beginning and the final stage of the Middle Valday, the forest–tundra landscapes with inclusions of tundra–steppe associations predominated. During the optimum of Bryansk Interstade, the periglacial pine-birch formations were widespread.

Sedimentation and soil formation phases in the Ghardimaou Basin (northern Tunisia) during the Holocene

Chronological and stratigraphical interpretations as well as 14C-dates and geoarchaeological investigations of detailed profiles from the mid-Medjerda valley (northern Tunisia) allow us to reconstruct one late Pleistocene and four Holocene sedimentation cycles within the floodplain area. Initial results from pedological examinations, including thin sections, indicate a latest Pleistocene and three Holocene soil formation periods. Our observations from the Medjerda valley are discussed in relation to current research in the southwestern Mediterranean region. The Crise Romaine—shown in the headwaters of the Medjerda river system by thick cobble accumulations—is exhibited in the basin region by a clear accentuation of the water level amplitude. Catastrophic flooding can be observed for the first time in the late Roman period. After soil formation during Middle Ages, ending at about 450 BP, flooding again increased.

Palaeoclimate, sedimentation and soil development during the Last Glacial Stage (Devensian), Heathrow Airport, London, UK

The Langley Silt Complex, overlying the Taplow Terrace of the river Thames at Prospect Park, near Heathrow Airport, west of London is described in terms of lithology, carbonate content, organic carbon content, particle size characteristic, macrostructure, micromorphology and stratigraphic position. The Langley Silts were deposited by wind or water in cold climate conditions and include evidence for the development of periglacial structures and for Devensian Lateglacial and Holocene soil formation. The Langley Silts rest upon a Last Interglacial (Ipswichian, OIS 5e) soil developed in the Taplow Gravel deposited during the previous cold stage (OIS 6). During the Early Devensian, and the Dimlington Stadial and Younger Dryas of the Late Devensian wind deposited the silts, and during the Middle Devensian wind and surface wash built up a laminated silt and sand. During the Middle Devensian, seasonal dessication formed non-sorted polygonal patterns as this laminated unit aggraded, but this process ceased with the return to loess deposition in the Late Devensian. Argillic soil development occurred during the Windermere Interstadial only to be disrupted by ground ice processes during the succeeding Younger Dryas cold phase. The site provides one of the most complete sedimentary sequences through the Last Glacial Stage in Britain and confirms recent interpretations of soil development and evidence for aeolian deposition in Britain during the Lateglacial.

Late Holocene soil formation in the valley of the River Yenisei, Central Siberia

Alluvial sod soil sequences from the 9 m terrace in the valley of the River Yenisei were used to reconstruct the paleoecological history and paleohydrological regime of the river. The terrace consists of an Early Holocene (5000–>6000 BP) sequence of alluvial sands and loamy sands and a Late Holocene sequence which has been transformed by soil development. Analyses of organic matter extracted from buried soils in two sections and comparisons with pollen assemblages suggest that the ratio of carbon in humic acids to that in fulvic acids and particular fractions of the humic or fulvic acids (termed `typical fractions') record changing conditions of regional environment.

Relict features of paleosols formed on loess and their age

Loess deposits of the last glaciation served as parent material for Holocene soil formation in the periglacial zone of the central Russian Plain. Recent (Holocene) soils as well as parent material contain textural features inherited from the last cryogenic phase of the Late Pleistocene. They are evidenced by detailed investigations of soil profiles carried out in the areas of development of the relict cryogenic microrelief. In the present study microstratigraphic methods were used to analyze the characteristics of soil profiles and their genetic horizons in trenches. Micromorphological studies in thin sections and radiocarbon dates indicate phases of Holocene development. Results acquired this way can be instrumental in age identification of distinguished soil features (since Late Pleistocene onwards).

Observations on holocene soil formation and morphodynamic activity in non-calcareous regions of the Iberian Peninsula

Summary Red fersiallitic soil relicts in non-calcareous regions (granite, schist, Tertiary sediments) of the Iberian peninsula have been studied stratigraphically in order to define the late Pleistocene/Holocene succession of morphodynamic and pedogenic phases. A late or post-Wurm age of the soil formation is suggested by the widespread admixture of loess to the slope deposits which form the parent material of the soil. The pedogenic processes (rubefaction, formation and translocation of clay) were interrupted by erosional impacts that led to an extensive removal of the soil cover. Two erosional phases are recognized: The recent intermittent wash processes on permanent fields connected with colluviation, and an earlier phase of erosion and slope deposition, the impact of which can be recognized in almost all soil relicts as a discontinuity cutting the A- or B-horizon of the soil. As these truncated soil remnants as well as the covering slope sediment of this phase (reworked A- or B-horizon material) have been subjected to subsequent pedogenic alteration it is suggested that the two erosional phases were separated by a period of relative surface stability. Radiocarbon dates from two sites provided a C14-age of about 4000 years B.P. for the earlier erosion impact. Most prominent of the subsequent pedogenic alterations is the development of a bleached horizon due to dissolution and leaching of iron from rubified soil horizons or layers. This alteration is connected with the vegetational change from oak-pine-forest to ericaceae scrub that begins around 2500 to 1500 years B.P.. While agricultural operations are the obvious cause of the recent erosion, climatic fluctuation may have precipitated the earlier phase of post-pedogenic morphodynamic activity.

On soil genesis In temperate humid climate. 6. The formation of a glossudalf in loess (silt loam).

In a well-drained gray brown podzolic soil (in S. Limburg), considered to be a Holocene soil formation in originally calcareous wind deposits, continuing development of the textural B horizon under the infiltration conditions occurring in flat areas leads to polygonal cracking in dry periods. In the wet season the soil surrounding these cracks becomes saturated. Reduction processes arise, leading to bleaching, and the appearance, in vertical sections, of light-coloured tongues bordered with a yellowish red band, and at some distance, Mn mottles and concretions. In the tongues strong clay leaching occurs. The largest amount of micro-morphologically determined orientated clay bodies (notably channel and ped argillans) occurs in the B3 horizon, whereas the B2t horizon has the highest clay content. Classification of the profile as an aquic glossudalf was based on a consideration of chemical and morphological data. (Abstract retrieved from CAB Abstracts by CABI’s permission)